Error -17 is -EEXIST (check /usr/include/asm/errno.h, included from /usr/include/linux/errno.h, which was included from /usr/include/bits/errno.h, which was included from /usr/include/errno.h, the header file from which all the error numbers get symbols).

Looking at the 2.4.19 kernel source for fs/devfs/base.c, I see that it looks like it returns -EEXIST if the directory entry (a.k.a. file or device) that it's trying to create or register already exists.

If you remove (modprobe -r) NVdriver, manually delete /dev/nvidia*, and then try to modprobe NVdriver, does it work?